The present invention relates to polymers of N,N,N-trialkylammoniumalkyl (meth)acrylates, to a process for their preparation and to their use for the biocidal finishing of surfaces or textiles.
For various reasons it may be necessary to give hard surfaces or textiles a biocidal finishing. This is intended to prevent microorganisms from being able to settle on said substrates and, more particularly, without repeated disinfection thereof using biocidal compositions.
Coating compositions for hard surfaces and textiles are known in principle.
Thus, DE-A-100 62 355 discloses copolymers for the coating of hard surfaces or of textiles which include anionic vinyl monomers and quaternary ammonium acrylates as comonomers. A biocidal action of such copolymers is not disclosed.
DE-A-199 21 894 discloses a process for the biocidal finishing of surfaces in which polymers of at least aliphatically monounsaturated monomers of the formula
R1NRaRb3Rc4Xd
where R1=H, branched, unbranched or cyclic, saturated or unsaturated hydrocarbon radical having up to 50 carbon atoms, which may be substituted by O, N or S atoms,
R2, R3, R4=H, branched, unbranched or cyclic saturated or unsaturated hydrocarbon radical having up to 25 carbon atoms, which may be substituted by O, N or S atoms, where R2, R3, R4 are identical or different,
X: an anion,
a, b, c, d: in each case 0 or 1 are used. Examples of monomers containing quaternary nitrogen groups are 2-methacryloyloxyethyltrimethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium sulfate, 3-methacryloylaminopropyltrimethylammonium chloride, N,N,N-trimethyl-3-(2-methyl-1-oxo-2-propenylamino)-1-propaneammonium chloride; N,N,N-triethyl-2-(1-oxo-2-propenylamino)ethaneammonium, N,N,N-trimethyletheneammonium bromide.
DE-A-199 21 904 discloses polymers which are suitable for the biocidal finishing of surfaces. These must be constructed from monomers which contain at least one quaternary amino group. The document names a series of suitable monomers with methyl, ethyl or benzyl substitution on the nitrogen atom.
It has been recognized that the polymeric coating compositions of the prior art are in need of improvement with regard to their biocidal action.
The object of the invention was therefore to discover novel polymers which can be applied to surfaces or textiles, and develop a biocidal action thereon.
Surprisingly, we have found that polymers of N,N,N-trialkylammoniumalkyl (meth)acrylates have these required properties if they carry long alkyl chains.
The invention therefore provides polymers consisting essentially of structural units of the formula (1) 
in which
R1 is a C1-C4-alkylene group
R2, R3 independently of one another, are a C8-C12-alkyl or alkenyl group
R4 is methyl or ethyl
R5 is hydrogen or methyl
and whose molecular weight is between 1000 and 100000 g/mol.
The invention further provides polymers consisting essentially of structural units of the formula (2) 
in which R1, R2, R3 and R5 have the meanings given above, and which have a molecular weight of from 1000 to 100000 g/mol.
The term xe2x80x9cessentiallyxe2x80x9d here means that the polymers according to the invention do not contain any other structural units which notably influence the properties of the polymers apart from those which conform to the formulae 1 and 2. It is assumed that the polymers can preferably comprise at most 2 mol %, in particular at most 0.5 mol %, of other structural units apart from formulae 1 and 2 without their properties being notably changed.
The polymers of the formula 1 can be prepared from the polymers of the formula 2 by quaternization. The polymers of the formula 2 therefore represent an intermediate for the polymers of the formula 1.
The invention further provides a process for the preparation of polymers of the formula 1 by reacting polymers of the formula 2 with a methylating or ethylating agent.
The invention further provides a process for the preparation of polymers of the formula 1 by transesterifying a (meth)acrylic alkyl ester, preferably a methyl ester, with a compound of the formula 3 to give the corresponding (meth)acrylic ester, then alkylating this transesterified product with a methylating or ethylating agent to give the quaternary ammonium compound, and subjecting this quaternary ammonium compound to free-radical polymerization.
The invention further provides a process for the preparation of polymers of the formula 2, by either
A) reaction of a compound of the formula 3
HOxe2x80x94R1xe2x80x94NR2R3xe2x80x83xe2x80x83(3)
with methyl (meth)acrylate in the presence of an esterification catalyst with removal of the methanol which forms during the reaction by distillation, and subsequent free-radical polymerizatioin of the resulting product,
or
B) reaction of a methyl polymethacrylate with a compound of the formula 3 in the presence of an esterification catalyst with removal of the methanol which forms during the reaction by distillation.
The invention further provides for the use of polymers of the formula 1 for the biocidal finishing of surfaces and textiles.
R1 is preferably an ethylene or propylene radical, in particular an ethylene radical.
R2 and R3 are preferably both the same radical. It is particularly preferred that R2 and R3 are octyl or decyl radicals, especially decyl radicals.
R4 is preferably a methyl radical,
R5 is preferably a methyl radical.
In a particularly preferred embodiment, the polymers according to the invention are those in which R1=ethylene, R2=R3=decyl, R4=R5=methyl.
The molecular weights of the polymers of the formula 1 according to the invention are preferably between 2000 and 60000 g/mol, in particular between 5000 and 40000 g/mol.
The quaternization of the nitrogen atom both in the polymers according to formula 2 to give the polymers according to formula 1, and also in the monomers is preferably carried out using an alkyl sulfate, or an alkyl halide. Particular preference is given to dimethyl sulfate or methyl chloride.
The transesterification of the (meth)acrylic methyl ester with the compound of the formula 3 is preferably carried out in the presence of a basic esterification catalyst. Preferred catalysts are alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides and organic tin compounds. Particular preference is given to Sn(C4H9)4, K2CO3, KOH, Ca(OH)2, NaOH, NaOCH3, Li2CO3 and LiOH.
The free-radical polymerization of the compound obtained from a reaction of (meth)acrylic methyl ester and the compound of the formula 3 takes place by processes known in the prior art.
Suitable initiators for the process according to the invention are the initiators for free-radical polymerisations known in the prior art, preferably aziosobutyronitrile. The weight ratio of compounds of the formula 2 to the initiator is preferably less than 600:1, in particular less than 250:1.
The polymerization is preferably carried out at temperatures between 50 and 80xc2x0 C., in particular 55 to 70xc2x0 C. The at least single increase in the reaction temperature by at least 10xc2x0 C. preferably takes place after 40% of the total reaction time, in particular up to 50% of the total reaction time.
The polymerization can be carried out in a solvent. Examples of suitable solvents are lower alcohols and lower alkylbenzenes, preferably methanol or toluene. The polymerization can also be carried out in the absence of solvents.
If a solvent is used, then the concentrations of the monomers are preferably about 30 to 50% by weight.
For use as a biocidal finishing agent, the polymer according to formula 1 in alcoholic and/or aqueous solution with a content of 1-50 g/l is applied to the surfaces and textiles to be treated. The polymers according to formula 1 are suitable in particular for the finishing of wool, polyester, polyamide and cotton.